Control valves that are installed in conduits, generally of big size, into which a fluid under the form of gas or liquid, such as oil, circulates, have long been known.
Such valves control an opening and a closure and are generally, but not necessarily, installed for controlling the delivery flow and for managing emergency situations by intercepting the fluid or deviating it to a secondary conduit.
One type of these valves is called HIPPS (High Integrity Pressure Protection System). This type of valves are projected for having a high safety level and are employed for protecting systems from accidental over-pressure in the conduit. An application example for these types of valves is that of the installation in proximity of a containment tank into which fluid in pressure is pushed. One or more sensors register the pressure in the circuit or in the container and, in case of an excessive rising of the pressure value, control the opening of one or more of such valves which allow an outlet and therefore a sudden pressure drop.
In the background art, different documents are present that describe various solutions adopted for moving the shutter inside these valves.
One of these is, for example, mentioned in U.S. Pat. No. 4,327,757 that describes a valve provided with an inlet for the fluid, an outlet and a path that puts in communication the inlet with the outlet. Inside the path a piston is arranged coaxially with the inlet and outlet and it is mobile between a position that obstructs the path of the fluid and a position in which the fluid can freely deflow from the inlet towards the outlet. The valve connected horizontally to the conduit has an activation system of the piston constituted of a vertical stem having a dented end which engages with a corresponding helicoidal gear tooth obtained on a terminal part of a horizontal rod to which the piston (or shutter) is connected on the opposite side. The vertical rod is rotatable in the clockwise or anti-clockwise sense, thus causing, by means of the engaging of the teeth, a translation in a direction or in the opposite direction of the horizontal rod, and therefore of the piston.
This type of solution, that in fact includes the use of toothed gears, has the technical problem of suffering significant wear of the parts in contact between them. The strong acting pressures often conduct to the quick wear of the parts and therefore it is necessary to over-dimension the system to guarantee a longer duration. Moreover, this solution adapts badly to situations in which the piston must move at high opening/closing speeds. Therefore, it is not possible to have high movement speeds or vary them in an easy way without the risk of breakages of the teeth in contact between them and excessive wear.